As the title says, I have a 6-month gap on my resume (November '15 to May '16) where no employment is listed. I have a pretty good reason, and one that makes for an okay story as well. I was working a job abroad, but my visa program was terminated in response to the migrant crisis in Europe and as a result, had to leave my job at the last minute. I returned to the US, applied and was accepted into Teach for America, but had 6 months of lag time before TFA actually started, lived at home and used that time to study for the LSAT, finance a car by driving for Uber and Lyft, and spend time with my family.

Is it worth it to write all of this in an addendum (I already have a PS about something else that I am very happy with) or will law schools not even notice/care about a 6-month gap in my resume?

For context:LSAT 172UPGA 3.84Bachelors in 2014, so my resume includes almost 5 years of post-college employment info

If you have 5 years of otherwise nearly continuous work experience , I would not worry about a 6 month gap (unless that 6 month gap is current, which it seems like yours is not). Especially not if it was before a program like TFA that has a defined start date. Many adcomms themselves did TFA, so they know that it has a defined start date. And especially not if what you did during that period was drive uber and study for LSAT (if you did something really interesting during that period, then maybe....)